Sierra Club Opposes Tempe Power Plant

The Sierra Club filed an appeal to the air-quality permit for the natural-gas plant overhaul in Tempe that Arizona Public Service Co. is undertaking.

The utility wants to close part of the Ocotillo Power Plant near Tempe Marketplace and replace it with more powerful and efficient generators (AZBEX, April 3, 2015).

But the Sierra Club is opposed to how APS would operate the new generators at the plant, which could result in carbon-dioxide emissions akin to a coal-fired power plant, the group said.

But the Sierra Club in its appeal contends that APS plans to idle the generators at low capacity in order to ramp it up quickly as solar power production on the power grid declines. That idling is inefficient and results in unnecessary emissions, the group said in its petition to the appeals board of the Environmental Protection Agency.

Sierra Club suggests APS use large batteries to store electricity from the plant to quickly ramp up and meet electricity demand without running the generators on standby.

Arizona Public Service Co. plans to spend $600M to $700M dismantling the two 110-megawatt steam generators at Ocotillo and replacing them with the five shorter generators that use less water and fuel to make electricity.

APS initially planned to complete the project in 2018. Construction must wait for the appeal process to conclude.